DESCRIPTION: (Applicant's Abstract) Disruptive disorders, such as conduct disorder (CD) and attention deficit hyperactivity disorder (ADHD), are associated with an increased risk for drug dependence, crime and other antisocial behaviors. These individuals tend to be impulsive, are frequently aggressive and attempts to modify such behavior are usually not successful. Other people, observing the behavior patterns of CD and ADHD adolescents and adults, have difficulty understanding why these patterns persist. We propose that the manner in which the behavior of CD and ADHD individuals interacts with their environment is in certain contexts very different from such interactions among the majority of the population. Specifically, CD and ADHD individuals are not sensitive to environmental stimuli signaling impending aversive stimuli or negative outcomes, or even the presentation of aversive stimuli in attempt to change their behavior. Our application will compare the behavior of three groups of subjects under laboratory conditions. We will define these three groups using laboratory measures of aggression and impulsivity. Group 1- AGG+IMP+ defined as high in both aggression and impulsivity, Group 2- AGG+IMP- high in aggression and low impulsivity and Group 3-AGG-IMP- low in both aggression and impulsivity. We propose to extend these earlier findings relying on behavioral measures of "traits" which have found to be predictive of disruptive behaviors and drug dependence. All previous studies have examined only nonsocial behavior, in this application we propose to study a social behavior, aggression. We also propose to measure impulsivity via behavioral testing which other studies have not done. Risk-taking will also be compared under laboratory conditions. The proposed research will provide information about behavioral mechanisms operating in certain individuals who exhibit high or low probabilities of aggressive and/or impulsive behavior. Members of the three behaviorally defined groups will be described in terms of diagnostic categories: Conduct Disorder, ADHD and other personality dimensions. The three behavioral groups may differ in the manner in which they respond to aversive environmental stimuli and the effect such stimuli have on subsequent behavior. CD and ADHD individuals also are more likely to be impulsive and aggressive, which makes them less able to inhibit their own behavior. These aggressive and/or impulsive tendencies interact with the behavioral mechanisms discussed above to place such individuals at high risk for drug dependence, crime and other antisocial behavior. The behavioral mechanisms operating which cause a lack of sensitivity to aversive stimuli result in CD and ADHD individuals being less sensitive to the effects of punishment, extinction, changes in probability of reward and less likely to change their behavior accordingly, and more likely to take risks even in the face of declining positive outcomes. Demonstrating such fundamental differences may lead to different approaches in attempts to modify antisocial behavior among high risk populations with such behavioral tendencies.